A multitude of sensors are presently in use to detect various types of gases and chemical compounds. Such sensors range from the common household smoke detector to those designed to detect deadly nerve gases. Many of these applications require sensors that are sensitive and relatively small in size.
Current sensing and detection technologies have a number of drawbacks such as poor sensitivity and selectivity for the target matter, relatively long analysis times, lack of portability, and relatively high costs. For some applications, detection sensitivities in the part per trillion range (ppt) are needed, but few techniques even approach such sensitivity levels. For example, explosive sensors must be able to detect target matter such as TNT with below part per billion (ppb) sensitivity. Similarly, chemical agent sensors must exhibit sub-ppb sensitivity and be capable of distinguishing the nerve agent class (GA, GB, GD, GF, VX) and the blistering agent class (HD, L, T) of chemical agents. Present sensor technology generally does not offer the capability of sensing concentrations below the ppb range.